Ignition Coil Bad?

[WoodRipper]

My Shindaiwa 345 stopped running and I soon found it had no spark. It's happened before and I've traced it to poor connections between the ignition coil and pulser modules. I cleaned those connections, put it back together and, sure enough, I had spark - for 2 or 3 pulls of the starter and then nothing again. I had some other things to do and it was several hours before I got back to it. Cleaned everything again, checked every wire for shorts and found none, put it back together - and got exactly the same result, spark for 2 pulls then dead.

Whatcha think? Ignition coils are no longer available for this saw, so I can't just get one and try it. Thanks in advance.

John

 

[Big_Wood]

So yer saying that saw has 2 seperate ignition units. A magneto and a coil. If it were me i would first unplug the kill switch and crank her over without letting the wire touch ground to see if there is spark, then check gaps between flywheel magnets and magneto. With that setup the magneto could either be sending intermitant pulses to the coil or the coil could have alot of resistance making it hard for the juice to get to the plug. You can test the resistance of the coil with an ohm metre. Don't know what the resistance is supposed to be for the coil in that saw but somebody on here may know. If the resistance reads infinite you know you got a bad coil. I just fixed a honda eu1000 with the same issue as you described. My theory on it which i may be wrong is when you crank over the engine a few times the magneto sends it's pulses to the coil but the juice can't get through the resistance of the coil fast enough to get it to the plug. After it sits for a bit the juice slowly makes it's way through the coil then the next time you crank it you get a couple sparks out of it until the juice built up in the coil depletes. It makes sense to me but i may be wrong. It's just a theory i thought up in my head. Somebody will be able to straighten me out. Anyways i tested the coil of the honda eu and the resistance was infinite. I had a parts one sitting around so i pulled the coil off of it for the other one and it ran like a top.

 

[troutmansawtech]

we are a shindaiwa dealer and have several used coils for most saws.i know of 3 i can put my hands on right now at the shop.and prob 1-2 new modules.let me know and ill give you a good price.john

 

[WoodRipper]

Actually, there are 3 units that make up the ignition system on this saw. Here's a schematic (I hope):

View attachment 271984

The pulser is #8 on the schematic. I just changed it to a brand new one but still no spark, so that's not it. That leaves the coil, #10, or whatever #6 is. It is triggered by the flywheel, also. I put an ohm-meter across the leads from #6 and I measured some resistance on the highest range. However, on the coil, #10, I measured nothing but infinity. So, does that mean it's the coil for sure?

Thanks,

John

Correction: I realized I had not tested the coil correctly, so I checked it again and I got 1 on the 200M ohmmeter range and not infinity. Sorry for any confusion.

John

 

[Fish]

I used to be a Shindaiwa dealer and they gave me that "likely" or "should-be" crap on their multi component ignitions.....

Almost always, the coil was good, but that was just an observation from my wasted hundreds....

 

[Fish]

They always worded their manuals, using a particular multimeter, using words like "should" and "likely" if they are in or out of certain ranges.....

Etc. After talking with the techs, it was always a crap shoot. Many brands. Echo, Shindaiwa, Tecumseh, others......

 

[alderman]

Fish
Was this the only Shindaiwa model with the three part ignition? Seems I've heard about more 345's with bad ignitions than any of the others. Do you know why they would go with three parts when they could do the same job with two?